Floating shield for comminuting device



Aug. 18, 1959 w. H. LANNERT 2,900,081

FLOATING SHiELD FOR COMMINU'II'ING DEVICE Filed Feb. 21, 1955 2 Sheets-Sheet 1 Aug. 18, 1959 w. H. LANNERT 2,900,081

FLOATING SHIELD FOR COMMINUTING DEVICE Filed Feb. 21, 1955 2 Sheets-Sheet 2 Inga/aim, mama @JMW/, fijwmdw g 27 121461)? nited States Patent FLOATING SHIELD FOR COMMINUTING DEVICE William H. Lannert, Skokie, Ill., assignor to Chicago Pump Company, a corporation of Delaware Application February 21, 1955, Serial No. 489,651

7 Claims. (Cl. 210173) This invention relates to a floating shield for comminuting devices, and is Particularly concerned with means for retaining solids intercepted in a flowing stream of sewage adjacent the cutting cylinder in order to facilitate the action of teeth projecting laterally from the cylinder in picking up the solids and carrying them to a comb with which the teeth cooperate to comminute the solids.

The structure with which the shield of the present invention is used comprises a screen extending across an infiuent channel through which a stream of sewage flows and intercepting all solids too large to pass therethrough. The screen may be disposed vertically in the channel or may be inclined at any suitable angle. A cutting cylinder is rotatably mounted upstream of the screen and adjacent the upper end of the screen. The screen is provided with transversely spaced, longitudinally extending parallel screen elements, and the cylinder is provided with a plurality of series of laterally projecting teeth that are aligned transversely with the spaces between screen elements. The laterally projecting teeth are adapted to carry solids from the screen and transfer them to the vicinity of a comb. The teeth cooperate with notches provided in one edge of the comb to comminute the solids that are interengaged by the teeth and comb. The position of the cylinder is fixed relative to the screen and therefore the teeth of the cylinder can reach only the solids that have been intercepted by the screen in immediate proximity to the cylinder.

A simple, inexpensive rake engages the solids intercepted by the screen outside the range covered by the teeth projecting laterally from the cylinder, and moves them upwardly along the upper surface of the screen into the area that is reached by the teeth. Although one rake structure is specifically described in the following specification, it will be obvious that any suitable structure may be used.

In comminuting devices the cutting cylinder is rotated at a high rate of speed and has a tendency to throw solids outwardly from the cylinder. The force of the onflowing sewage ordinarily holds the solids against the cylinder and the comminuting process is eflicient. However, when the liquid level is low there is not always a suffi: cient flow of liquid to hold the solids against the cylinder, and the comminuting eificiency is lowered. It has also been found that when the liquid level is high the flowing liquid sometimes washes a substantial portion of the solids from the cylinder.

In accordance with the present invention a shield is pivotally secured to the apparatus near the top of the comb and extends transversely across the width of the screen. The shield is buoyant and moves pivotally in accordance with the rise or fall of the liquid level of the sewage stream. When the liquid level is low the shield forms a pocket spaced forwardly of the cylinder which retains the solids against the cylinder until the teeth carry them upwardly to the comb. When the liquid level is high the shield moves upwardly, but a portion of it projects below the liquid level and protects the cylinder to prevent the h 2,900,081 Patented Aug. 18, 1959 liquid from washing a substantial proportion of the solids from the cylinder.

The structure by which the above mentioned and other advantages of the invention are attained will be described in the following specification, taken in conjunction with the accompanying drawings, showing a preferred illustrative embodiment of the invention, in which:

Figure 1 is a fragmentary perspective View of a channel through which a stream of sewage flows, an inclined screen extending across the channel with its screen elements spaced transversely, and a floating shield positioned in front of the cylinder and pivotally secured to the apparatus adjacent the top of the comb;

Fig. 2 is a longitudinal sectional view, taken along the line 22 of Fig. 1, showing the shield in cross section and also showing its position relative to the cutting cylinder when the liquid level of the sewage stream is low; and

Fig. 3 is a fragmentary view similar to Fig. 2, showing the position of the shield when the liquid level is high.

In the drawings, reference numeral 2 indicates an influent channel through which flows unscreened sewage carrying solids, and 3 indicates the effluent channel through which the screened sewage flows, along with the solids that are comminuted adjacent the upper end of the screen on which they accumulate. Channels 2 and 3 are parts of a single structure, preferably made of concrete.

A screen 4 is supported in inclined position in channel 2 by means of a pair of standards 5 extending upwardly from the bottom of the channel. Any form of screen may be used. The illustrative embodiment of the screen shown in the drawings comprises a plurality of flat metal ribbons disposed edgewise and held in parallel transversely spaced relationship. Suitable supports extending laterally from the side walls of the channel can be used instead of standards 5, to support the upper end of screen 4, if desired. The lower end of the screen can be secured to the bottom of channel 2 in any suitable manner. The screen is illustrated as being inclined at approximately thirty degrees, but it will be understood that this angle may be varied, as desired.

Screen 4 comprises a frame 6 the outer edges of which are flush against the Walls of infiuent channel 2. Frame 6 is provided with a centrally disposed opening 7 across which a plurality of individual screen elements 8 extend. These screen elements are disposed edgewise and longitudinally of the screen, and are transversely spaced across the space between the longitudinal edges of frame 6. The screen elements are held under tension by any suitable means, such as the tensioning device described and claimed in the copending application of Carl H. Nordell, filed March 26, 1954, under Serial No. 418,944, which issued as Patent No. 2,727,627 on December 20, 1955. The tensioning device includes a plurality of individual leaf springs 9 each holding the upper end of a screen element 8. Each leaf spring extends past a rib 10 projecting from a plate 11 and is held in place by a bolt 12. The edgewise disposition of individual screen elements in a screen is claimed in the copending application of Carl H. Nordell, Serial No. 451,130, filed August 20, 1954 as a continuation-in-part of application Serial No 278,822, now abandoned, which was a division of application Serial No. 261,973, filed December 17, 1951 which issued as Patent No. 2,750,044 on June 12, 1956.

A cutting cylinder 13, disposed horizontally relative to the screen, is rotatably mounted in bearings 14 supported on brackets 15 secured to the upper surface of frame 6. The cutting cylinder is provided at one end with a housing 16 which contains gears (not shown) operatively connected, by means of a shaft 17, to a motor (not shown) for rotating the cylinder. A sleeve 18 encloses shaft 17. Cylinder 13 is provided with a plurality of series of laterally extending teeth 19. The teeth are 3 spaced longitudinally of the cylinder to coincide with the spacing between individual screen elements so that they enter the spaces between adjacent screen elements 8 as the cylinder rotates.

A stationary comb 20 extending parallel to the longitudinal axis of cuttingcylinder 13 is secured at its oppos'ite ends to a pair of brackets 21 extending upwardly from opposite edge portions of frame 6. The lower longitudinal edge of comb 20 is provided with longitudinally spaced notches or recesses 22 and is positioned adjacent the peripheral surface of the cylinder along a line spaced radially from the line of contact between the cylinder and screen elements 8. Notches 22 are aligned with teeth 19 which cooperate therewith to comminute solids carried by the teeth as they pass through the notches.

The shield 23 comprises a central portion comprising a sheet of metal or other suitable material folded to form a wide bottom 24 and two side walls 25 and 26 curved toward each other to meet in a narrow top 27 giving the shield the shape of a tear drop in cross section. The shield extends transversely across the screen a short distance forwardly of cylinder 13. Each end of the shield is closed by an end wall 28 shaped to conform to the cross sectional contour of the walls 25 and 26. The end walls 28 are sealed to walls 25 and 26 to make the shield water tight so that it will act as a float. The shield is lifted upwardly by a raise in the liquid level of the sewage stream, and is moved downwardly by a lowering of the liquid level. Regardless of the liquid level of the sewage stream, the lower portion of the .floating shield is always maintained partially immersed in the stream. Bearing 14 is provided with a laterally projecting car 29, and housing 16 is provided with a similar ear 30 which serve as support members for the shield. End walls 28 are each provided with integral extensions 31 which are pivoted to ears 29 and 30, as indicated at 32 and 33, respectively. A stud 31 projects downwardly from one or both of the extensions 31 in position to abut the upper edge of comb 20 to limit the downward movement of shield 23 and thereby prevent it from swinging towards the cutting cylinder far enough to engage teeth 19.

In the lowermost position of shield 23, shown in Fig. 2, the shield is comparatively close to cylinder 13 and forms a pocket to hold solids engaged by teeth 19 from falling away from the cylinder as they are being carried towards comb 20. As the liquid level of the flowing sewage rises, the shield rises with it to permit continued access of the solids to the cylinder and to prevent undue interference with the flow of the sewage. Maintaining the depth of immersion of the lower portion of the shield constant as the liquid level rises also prevents solids, such as rags, from accumulating on the surface of the shield. The curved shape of the bottom of the shield causes any solids that flow against the shield to move downwardly into engagement with the screen or the cylinder. The weight of the shield keeps its lower end constantly immersed to a predetermined extent in the sewage so that it always acts as a baffleplate to deflect the flowing sewage downwardly in front of the cylinder to form a downwardly moving curtain of liquid that minimizes the possibility of the flowing liquid washing the solids from the cylinder.

A transfer device or rake, adapted to be recirocated longitudinally of the screen, is provided for the purpose of pushing solids that are intercepted by the portion of the screen out of the range of teeth 19 upwardly along the screen into the range of the teeth. The transfer device shown in Fig. 2 comprises a plurality of short fingers 34 rigidly secured in transversely spaced relationship to a transverse member (not shown) having vertical end members 35. Each finger is positioned between adjacent screen elements 8, and is of substantially the same thickness as the distance between adjacent screen'elements so that the fingers will wipe the screen elements clean as 4 the rake is moved longitudinally of the screen towards cylinder 13.

The structure at opposite longitudinal edges of screen frame 6 is the same, and therefore the structure on only one side will be described. The longitudinal edge of screen frame 6 is provided with a downwardly extending flange 36 fitting against the walls of channel 2. A guide member 37 is rigidly secured to flange 36 with its side wall 38 fitting against the inner surface of the flange. Guide member 37 has a top wall 39 and a bottom wall 40 extending inwardly at right angles to side wall 38. The top wall 39 of the guide member is provided with a downwardly curved resilient extension 41 at its lower end and a similar downwardly curved extension 42 at its upper end. The lower wall 40 is provided at its lower end with a similar extension 43 parallel to extension 41 and'at its upper end with a similar extension 44 parallel to extension 42. These extensions are preferably made of spring steel.

The rake structure is the same at both ends-and therefore only one end Will be described. A flat plate 45 is pivotally secured to the end member 35 by a stud 46. A link 47 pivotally connected at one end to a lug 48 projecting from plate 45, as indicated at 49, is pivotally connected at its other end to a clevis 50, as indicated at 51. Clevis 50 is secured to one end of a piston rod 52. The opposite end of piston rod 52 is slidably mounted in a cylinder 53 (Fig. 1) which is mounted adjacent the upper portion of frame 6. Cylinder 53 is operated by a conventional hydraulic system, and reciprocation of piston rod 52' reciprocates the rake longitudinally of the screen.

Stud 46 is provided on the outer end with a roller 54 rotatably mounted in guide member 37. The diameter of roller 54 is approximately equal to the distance between top and bottom walls 39 and 40 of the guide member. A roller '55, similar "to roller 54, is mounted on a stud 56 projecting outwardly from plate 45. Rollers 54 and 55 are aligned with each other and are the same size so that they fit snugly in guide member 37 in longitudinally spaced relationship. Plate 45 is also provided with pins 57 and 58 projecting into the plane member 35. Pins 57 and 58 serve as stop members to limit the pivotal movement of member 35 about stud 46, pin 57 abutting one edge of member 35 when it extends perpendicularly to plate 45, and pin 58 abutting the opposite edge of member 35 when it is pushed forwardly by rod 52.

The operation of the rake mechanism is very simple. As piston rod '52 pulls the rake upwardly longitudinally of the screen, member 35 is pulled rearwardly against pin 57 to hold rake fingers 34 percpendicular to plate 45. In this position the length of fingers 34 causes them to project above the upper surface of screen elements 8 so that all solids intercepted by the screen are pushed upwardly along the surface of the screen until piston rod 52 is fully retracted. At the upper end of its movement the rake is positioned with its fingers in proximity to cylinder 13. Shield 23 holds the solids adjacent cylinder 13 while teeth 19 engage the solids and carry them to comb 20for comminution.

q The downwardly extending curve between extensions 42 and 44 of the guide member retards the movement of roller 55 in the opposite direction. This retarding effect is sufficient to cause rod 52 to push member 35 pivotally about stud 46- until it abuts pin 58. In this position rake fingers 34 are inclined forwardly. Continued downward movement of piston rod 52 lifts roller 55 up the curved surface of extension 44. Since the rear end of plate 45 is raised withroller 55, pin 58 is moved forwardly anddownwardly. The piston rod continues to push member. 35 forwardly against pin 58 thereby causing the rake teeth to be inclined so as to bring the upper edges of the rake teeth approximately flush with the upper surface of screen elements 8, as shown in dotted lines in Fig. '2. The rake teeth remain in this position throughout the downward movement of the rake until roller 54 reaches the extension 43 at the forward end of its movement. The retraction of rake fingers 34 enables them to move downwardly along the screen without disturbing the solids that have been intercepted by the screen.

The movement of roller 46 on to extension 43 causes it to resist upward movement of the rake until member 35 is pulled upwardly into abutting relationship with pin 57. Continued upward movement of piston rod 52 lifts roller 46 on to bottom wall 40 of the guide member and causes the rake fingers to project above the upper surface of the screen for the upward movement of the rake.

While I have described a preferred embodiment of my invention in considerable detail, it will be understood that the description thereof is intended to be illustrative, rather than restrictive, as many details may be modified or changed without departing from the spirit or scope of the invention. Accordingly, I do not desire to be restricted to the exact structure described.

I claim:

1. In combination with a comminuting device comprising a screen extending across an influent channel to intercept solids from a stream of sewage containing solids flowing through said channel, and a cutting cylinder extending transversely of said screen in proximity to the upstream surface of said screen, said cylinder being adapted to move solids from said screen into an area where they are comminuted, a pivoted shield extending transversely of said screen upstream of and in close proximity to said cutting cylinder to protect solids on said cutting cylinder against accidental displacement therefrom, said shield being movable vertically about its pivot in response to variations in the liquid level of said sewage.

2. In combination with a comminuting device comprising a screen extending across an influent channel to intercept solids from a stream of sewage containing solids flowing through said channel, and a cutting cylinder extending transversely of said screen in proximity to the upstream surface of said screen, said cylinder being adapted to move solids from said screen into an area where they are comminuted, a pair of support members positioned adjacent opposite sides of said channel above said cylinder, and a shield pivotally mounted on said support members, said shield extending transversely of said screen in close proximity to the upstream surface of said cylinder to protect solids on said cylinder from being washed therefrom by the liquid of the flowing sewage, said shield being movable about its pivot 'by changes in the liquid level of said sewage.

3. In combination with a comminuting device comprising a screen extending across an influent channel to intercept solids from a stream of sewage containing solids flowing through said channel, and a cutting cylinder extending transversely of said screen in proximity to the upstream surface of said screen, said cylinder being adapted to move solids from said screen into an area where they are comminuted, a pair of support members positioned adjacent opposite sides of said channel, and a shield pivotally mounted on said support members, said shield extending transversely of said screen in proximity to the upstream surface of said cylinder to protect solids on said cylinder from being washed therefrom by the liquid of the flowing sewage, said shield being adapted to swing towards said cylinder as the liquid level of said sewage stream recedes, and means to limit the movement of said shield towards said cylinder to maintain a minimum fixed spaced relationship therebetween.

4. In combination with a comminuting device comprising a screen extending across an influent channel to intercept solids from a stream of sewage containing solids flowing through said channel, and a cutting cylinder extending transversely of said screen in proximity to the upstream surface of said screen, said cylinder being adapted to move solids from said screen into an area where they are comminuted, a pair of support members positioned adjacent opposite sides of said channel above said cylinder, and a floating shield positioned in close proximity to the upstream surface of said cylinder, said shield' being provided at its opposite ends with integral extensions pivoted to said support members to swing upwardly and downwardly in response to changes in the liquid level of said sewage, said shield in its lowermost position forming a pocket adjacent said cylinder to retain solids against said cylinder and in its uppermost position having its lowermost portion immersed in the stream of sewage to deflect the flow of sewage downwardly and thereby protect solids on said cylinder from being washed therefrom by the liquid of the flowing sewage.

5. In combination with a comminuting device comprising a screen extending across an influent channel to intercept solids from a stream of sewage containing solids flowing through said channel, and a cutting cylinder extending transversely of said screen in proximity to the upstream surface of said screen, said cylinder being adapted to move solids from said screen into an area where they are comminuted, a pair of support members positioned adjacent opposite sides of said channel, and a floating shield positioned in proximity to the upstream surface of said cylinder, said shield being provided at its opposite ends with integral extensions pivoted to said support members to swing upwardly and downwardly in response to changes in the liquid level of said sewage, and means projecting from one of said extensions and engageable with a part of said comminuting device upon downward movement of said floating shield to limit the downward movement of said floating shield to prevent contact of said shield with said cylinder, said shield in its lowermost position being positioned sufliciently close to said cylinder to hold solids against it.

6. In combination with a comminuting device comprising a screen extending across an influent channel to intercept solids from a stream of sewage containing solids flowing through said channel, a cutting cylinder extending transversely of said screen in proximity to the upstream surface of said screen, said cylinder being adapted to move solids from said screen into an area where they are comminuted, and a rake reciprocable longitudinally of said screen to move solids along the upper surface of said screen into engagement with said cylinder, a shield pivoted to said comminuting device adjacent said cylinder and movable pivotally in response to changes in the liquid level of said sewage, and means projecting from said shield and engageable with a part of said comminuting device upon downward movement of said floating shield to limit the downward movement of said floating shield to prevent contact of said shield with said cylinder, said shield in its lowermost position being positioned sufficiently close to said cylinder to hold solids against it.

7. In combination with a comminuting device comprising a screen extending across an influent channel to intercept solids from a stream of sewage containing solids flowing through said channel, a cutting cylinder extending transversely of said screen in proximity to the upstream surface of said screen adjacent the upper end of said screen, said cylinder being adapted to move solids from said screen into an area where they are comminuted, a rake reciprocable longitudinally of said screen to move solids along the upper surface of said screen into engagement with said cylinder, and a shield pivoted to said comminuting device adjacent said cylinder and movable pivotally in response to changes in the liquid level of said sewage, said shield in its lowermost position being adapted to retain solids against said cylinder and in its uppermost position having its lowermost portion immersed in the stream of sewage to deflect the flow of sewage downwardly and thereby protect solids on said cylinder from being washed therefrom by the liquid of the flowing sewage.

(References on following page) 7 References Cited in the file of this patent 2,380,025 UNITED STAT-ES PATENTS 2,672,985

1,109,385 Allison Sept. -1, 1914 2,199,788 Durdin May 7; 1940 45 ,756 2,328,297 Roberts Aug. 31, 1943 711,944

8 Chase July 10, 1945 Nordell Mar. 23, 1954 FOREIGN PATENTS Great Britain Jan. 14, 1937 Great Britain July 14, 1954 

